Passengers have been told to expect delays during the day
The runway at Stansted Airport in Essex has reopened after snowfall forced it to close for about two hours.
Flights were suspended but the airport said services were now operating but passengers should expect delays.
More than 200 schools in the county have also been closed as several inches of snow fell overnight.
Essex Police said roads in west and north Essex were virtually impassable due to the snow, but dual carriageways in the south and motorways were clear.
Weather forecasters have predicted more snow for Essex over the next 24 hours and said temperatures were unlikely to get above freezing during the day.
A spokesman for Stansted said earlier: "We were able to deal with the early-morning wave of flights but the snow... got very heavy."
Essex Police said it had dealt with nearly 50 weather-related incidents ranging from road crashes to teenagers causing a nuisance with "anti-social snowballing" on Wednesday.
More snow has been predicted for the county in the next 24 hours
Ch Insp Richard Phillibrown, said: "The weather forecast is for the snow to continue through until this evening when we will then experience freezing temperatures and ice-related problems begin to play their part.
"Our advice to people is not to travel unless absolutely necessary, with children who are off school asked to be considerate with their play in the snow."
The Met Office said the cold weather had been the most prolonged spell of freezing conditions across the UK since December 1981.
The wintry weather is forecast to continue for the next couple of weeks, with further snowfall expected at times.
Warnings of either heavy snow or ice were in place for every county in England.